Embodiments of the invention relate to reconfigurable arrays, and more particularly to methods and systems for locally determining the configuration of the reconfigurable arrays.
Conventional ultrasound imaging systems comprise an array of ultrasonic transducers that are used to transmit an ultrasound beam and then receive the reflected beam from the object being studied. Ultrasound scanning comprises a series of measurements in which the focused ultrasonic wave is transmitted, the system switches to receive mode after a short time interval, and the reflected ultrasonic wave is received, beam-formed and processed for display. Typically, transmission and reception are focused in the same direction during each measurement to acquire data from a series of points along an acoustic beam or scan line. The receiver is continuously refocused along the scan line as the reflected ultrasonic waves are received.
For ultrasound imaging, the array typically has a multiplicity of transducers arranged in one or more rows and driven with separate signals in transmit. By selecting the time delay (or phase) and amplitude of the applied signals, the individual transducers in a given row can be controlled to produce ultrasonic waves that combine to form a net ultrasonic wave that travels along a preferred vector direction and is focused in a selected zone along the beam.
The same principles apply when the transducer probe is employed to receive the reflected sound in a receive mode. The voltages produced at the receiving transducers are summed so that the net signal is indicative of the ultrasound energy reflected from a single focal zone in the object. As with the transmission mode, this focused reception of the ultrasonic energy is achieved by imparting separate time delay (and/or phase shifts) and gains to the signal from each receiving transducer. The time delays are adjusted with increasing depth of the returned signal to provide dynamic focusing on receive.
The quality or resolution of the image formed is partly a function of the number of transducers that respectively constitute the transmit and receive apertures of the transducer array. Accordingly, to achieve high image quality, a large number of transducers are desirable for both two-and three-dimensional imaging applications. The ultrasound transducers are typically located in a transducer probe that is connected by a flexible cable to an electronics unit that processes the transducer signals and generates ultrasound images. The transducer probe may carry both ultrasound transmit circuitry and ultrasound receive circuitry.
In a typical ultrasound system, beam-forming is done using a large number of processing channels where each transducer element is linked to a single processing channel. In a reconfigurable array ultrasound transducer, multiple transducers are linked together and processed by a single ultrasound system channel simultaneously. This feature reduces the number of system channels that are required and thereby reduces the power, size and cost of the system.
A reconfigurable ultrasound array is one that allows groups of subelements to be connected together dynamically so that the shape of the resulting element can be made to match the shape of the wave front to improve performance and/or reduce channel count. The reconfigurable array consists of a large number of transducers that are linked together using semiconductor switches. Reconfigurability can be achieved using a switching network. Data to program the switch settings is typically calculated or stored in a controller system and then transferred over a digital data bus to the reconfigurable array. However, given the large number of transducers that need to be linked together using a large number of switches, there arises an information throughput bottleneck. This bottleneck places significant pressure on currently available technologies leading to difficult problems including data bit storage, data bus routing complexity, maximum required operating frequency, and power consumption.